This invention relates to a new and improved device for measurement and visual indication of both wind direction and wind speed. The primary use for the device is as a visual aircraft landing aid located at or near an airport to provide both wind direction and wind speed information to pilots desiring to land aircraft at the airport.
It is well known to aircraft pilots and others interested in aviation that knowledge of both the direction and the speed of horizontal surface winds in the immediate vicinity of the runway is very important to the pilot of an aircraft during landing maneuvers. Because of the importance of this information, the air traffic controller at each airport having a manned air traffic control tower routinely provides wind direction and wind speed information to every pilot calling the tower to request clearance for landing. But, pilots desiring to land at an airport which either does not have an air traffic control tower or has an unmanned air traffic control tower must rely on visual indications of wind direction and wind speed to acquire the information which he or she needs. And, of course, if the pilot loses radio contact with a manned air traffic control tower, he or she must rely on visual indications of wind direction and wind speed. While the wind itself can create natural visual indications of its direction and speed, it is desirable to have a visual aircraft landing aid located near the runway to provide the wind direction and wind speed information which is needed by the pilot.
Various devices which measure and visually indicate wind direction and which are suitable for use as visual aircraft landing aids are well known in the art. Only three basic types of the known devices are in general use as visual aircraft landing aids: the wind sock, the wind tetrahedron and the wind vane. While each type of known device has its own advantages and disadvantages, most pilots and other persons interested in aviation are of the opinion that all of the known devices are satisfactory for use during periods of high visibility. But, none of the known devices are satisfactory for use during the nighttime hours and other periods of low visibility.
Various devices for measuring and visually indicating wind direction have been proposed for use as visual aircraft landing aids during the nighttime hours and other periods of low visibility. For example, U.S. Pat. No. 1,605,086, issued to Watson in 1926 for a Device for Indicating the Direction of the Ground Wire to Aviators, discloses a "T" shaped wind vane having a light source which illuminates the top of the vane. The closely related concept of a dome-shaped wind direction indicating device having a fin or vane which is illuminated by an interior light source is disclosed in U.S. Pat. No. 3,537,310, issued to Barrett in 1968 for a Wind Direction Indicating Runway Marker. And, U.S. Pat. No. 1,942,039, issued to Tyler in 1929 for a Wind Signal, discloses a wind vane with means for projecting a light beam on a line parallel with the plane of the indicating vane or arrow. Furthermore, a conventional revolving airways beacon having means for deviating the light beam once during each revolution to indicate the wind direction to pilots of aircraft approaching the airport is disclosed in U.S. Pat. No. 1,989,095, issued to Howard in 1929 for a Wind Direction Indicating Airways Beacon.
None of the aforementioned devices are in general use as visual aircraft landing aids. Rather, the general practice at most airports is to use external light sources to illuminate the conventional wind sock(s), wind tetrahedron(s) or wind vane(s) in use at the particular airport during the nighttime hours and other periods of low visibility. Often, light colored stones or other light colored materials are placed on the ground in a circular area surrounding the device to improve the efficiency of the lighting sources used for illumination. Even when known devices are surrounded by such materials, it is often difficult for a pilot to locate the wind direction indicating device during his or her landing approach to the airport. Under the best of conditions, it is usually not possible for a pilot to see a conventional device for a distance of more than one mile during the nighttime hours or other periods of low visibility.
Because of its relatively low cost, the conventional wind sock is the most widely used device for measuring and visually indicating wind direction to a pilot desiring to land at an airport. But, it is well known by pilots and others interested in aviation that the visual indications of wind direction obtainable from a wind sock are often difficult to interpret. It is not unusual for a pilot to misjudge the wind direction when relying on a wind sock during periods of rapidly changing wind direction. And, such pilot errors occur much more frequently during the nighttime hours and other periods of low visibility.
Devices for measuring and visually indicating wind speed which are suitable for use as visual aircraft landing aids are unknown in the prior art. When a pilot desires to land his or her aircraft at an airport which does not have an air traffic control tower, has an unmanned tower or has a manned tower which the pilot is unable to contact by radio, he or she must rely on natural indications of wind speed, such as blowing dust, ripples and waves on nearby bodies of water, tree movement and the like. And, of course, such natural indications usually are not available to the pilot during the nighttime hours and other periods of low visibility. Thus, a substantial safety hazard exists for both the pilot and his or her passengers each time a landing is attempted under the aforementioned circumstances.